Does the face down ASET matter?

[DiamondsAndDior]

I noticed that Whiteflash AGS reports have both the regular ASET and the ASET of the stone face down (screenshot below). Does the face down ASET provide anything important on light return and/or does it matter what it looks like?

 

[kmoro]

As far as I know, it’s just to show the heart pattern (symmetry).

 

[gm89uk]

Only to show hearts.

 

[Karl_K]

Computer generated image using scan data, may or may not closely resemble a real image taken with the diamond in a h&a viewer.

 

[Texas Leaguer]

I noticed that Whiteflash AGS reports have both the regular ASET and the ASET of the stone face down (screenshot below). Does the face down ASET provide anything important on light return and/or does it matter what it looks like?

This is actually a fairly common question. In fact, AGSL has recently added a message below the light maps clarifying the purpose for the pavilion view. (yellow highlight)
“The face-down image on the right is provided solely for the purpose of communicating the optical precision of the cut”




The dual light map cert provides the maximum amount of graphical information on light performance and cut precision. Face up show light return/leakage, obstruction, and the degree of optical symmetry of the "arrows". Face down view is intended only to show the optical precision of the "hearts". Since the diamond is not viewed from this position light return/leakage is irrelevant in this map.

The computer generated light maps are derived from the same 3D scan as is put through the ray tracer to arrive at a light performance based cut grade. Since actual photography variables are eliminated, the computer generated maps are as accurate or more accurate than many photos posted to the internet. They are, however, only as good as the scan. But the scanners used at the labs are calibrated with regularity.

Idealy you would have both actual photos as well as dual light maps on the report to cross validate one another for maximum certainty.

You will typically note a bit more obscuration in the face-up map (blue), as they are printed at a 33% cone of obscuration, whereas ASET devices (used in photography) are set at 30 degrees. One of the reasons AGSL uses 33 is that the ray tracer looks at a range of obscuration levels and tilt angles.